Mentored Research Scientist Award for Tara M. Chaplin, Ph.D. This K01 application seeks support that is essential for my development as an independent interdisciplinary scientist. I have developed an important program of psychosocial research on gender, patterns of emotional response to stress, and the development of depression in adolescence. However, to fully understand the impact of emotional arousal patterns on adolescent psychopathology, I must incorporate biological aspects of emotion and must understand the role of emotion in both internalizing disorders such as depression and externalizing disorders such as substance abuse. Therefore, in this K01 application, I propose to acquire training in three areas: (a) developmental neurobiology models and measures of emotion and psychopathology; (b) substance abuse research; and (c) advanced data analytic techniques for repeated bio-psycho-social data and complex developmental models, including Linear Mixed Effects and Structural Equation Modeling. Training will be provided through intensive mentoring by a team of leading interdisciplinary scientists, and through guided readings, coursework, and attendance at conferences/meetings. I will also complete a research project examining the role of emotional response to stress in the development of substance use and depressive symptoms in 200 adolescents (aged 14-15 years), half of whom are at risk for the development of adjustment problems due to prenatal cocaine exposure. Prenatal cocaine exposure (PCE) is known to specifically impact emotional arousal systems and may also be a risk factor for substance use disorders and depression in adolescence. However, no published studies have followed PCE children into adolescence to test this possibility. The proposed study follows a well-characterized cohort of adolescents who have been studied since their birth. Half of the adolescents were prenatally exposed to cocaine and the other half were not exposed to substances, with both groups from low-income families. Adolescents will participate in a laboratory-based stress task (the Trier Social Stress Test, TSST) with detailed assessments of their emotional responses across bio-psychosocial domains. Adolescent's subjective emotion experience, observed emotion expression, cardiovascular arousal (HR, BP), and HPA-Axis arousal (cortisol levels) will be assessed before, during, and after the TSST. Adolescents will complete 6- and 12-month follow-up assessments of substance use/abuse and depression. Analyses will examine associations between emotional response to the stressor and increases in substance use and depressive symptoms by 12-month follow-up. Understanding possible mechanisms for the initiation and early escalation of substance use disorders and depression will inform the development of interventions for adolescents at risk and the proposed Award will enable me to contribute to this field.